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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS
General Certificate of Education Advanced Subsidiary Level
* 4 4 2 1 7 1 6 3 4 1 *
8780/04
PHYSICAL SCIENCE
Paper 4 Advanced Practical Skills
October/November 2013
1 hour 30 minutes
Candidates answer on the Question Paper.
Additional Materials:
As listed in the Confidential Instructions
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name on all the work you hand in.
Give details of the practical session and laboratory where appropriate, in the boxes provided.
Write in dark blue or black pen.
You may use a pencil for any diagrams or graphs.
Do not use staples, paper clips, highlighters, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer both questions.
You will be allowed to work with the apparatus for a maximum of 45 minutes for each question.
Electronic calculators may be used.
You are advised to show all working in calculations.
Session
Use of a Data Booklet is unnecessary.
Qualitative Analysis Notes are printed on pages 11 and 12.
Laboratory
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or
part question.
For Examiner’s Use
1
2
Total
This document consists of 10 printed pages and 2 blank pages.
DC (CW/JG) 62213/4
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BLANK PAGE
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3
1
You are going to investigate how the turning effect of a force depends on the angle through
which it acts.
For
Examiner’s
Use
The apparatus is set up as shown in Fig. 1.1, with the metre rule pivoted on a pin at point P.
The metre rule is uniform and point P is at the centre of the rule.
protractor
pivot P
thread
S
metre rule
rod R
protractor
weight
holder
e
clamp stand
B
clamp stand
A
thread T
Z
Fig. 1.1
(a) Pull the weight holder down a few centimetres and then release it. The weight holder
should move up and down until it comes to rest.
Adjust the position of the rod R so that thread S is perpendicular to the rule. This may be
done by changing the height of the rod R, or by moving clamp stand B sideways. Both
techniques may be useful during this experiment.
The angle between thread T and the 90° mark on the lower protractor is θ.
Measure and record the value of the angle θ.
θ = ..............................
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(b) You are going to measure θ at five different values of additional weight W added to the
weight holder.
Construct a table suitable for recording six sets of measurements of W and θ for values
of W in the range 0.20 N to 0.90 N. Include a column for values of cos θ.
(c) (i)
(ii)
Record in the table your value of θ from part (a). For this value of θ, W = 0.
For each weight W repeat the procedure in part (a). Ensure that thread S is
perpendicular to the metre rule before measuring θ.
Record your values of W and θ in your table.
(iii)
Calculate and record cos θ for each of the values of θ you have measured.
(d) (i)
On the grid provided, plot your values of W on the x-axis and cos θ on the y-axis.
Do not draw the best-fit line at this stage.
(ii)
Select one of your plotted points that you wish to repeat to improve the accuracy of
your data. Repeat this measurement.
1.
2.
Circle the point you are repeating.
Give a reason for repeating this measurement.
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3.
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Record the result of your repeated measurement in the space below.
Plot this point on the grid and label it Q.
8780/04/O/N/13
For
Examiner’s
Use
5
For
Examiner’s
Use
(iii)
Draw the straight line of best fit.
(iv)
Calculate the gradient of the graph. Show your working.
gradient = ......................................................
Question 1 continues on the next page.
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(e) The relationship between W and θ is
For
Examiner’s
Use
Z cos θ = W + k
where k is a constant and Z is the weight of Z.
Calculate the value of Z.
Z = ......................................................
(f)
Suggest, with a reason, a significant source of error in the experiment.
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[Total: 15]
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2
(a) You are to carry out a titration to determine the concentration of iron(II) ions in solution A.
You are provided with the following:
• A, an aqueous solution containing iron(II) ions
• B, a solution containing 0.0200 mol dm–3 of potassium manganate(VII)
• dilute sulfuric acid
(i)
Fill a burette with solution B.
Using the pipette, transfer 25.0 cm3 of A into a conical flask.
Add 10 cm3 of dilute sulfuric acid.
Titrate A with B until there is a permanent pale pink colour.
Perform a rough (trial) titration and two further titrations.
Record your titration results in the space below. Make sure that your recorded
results show the precision of your working.
(ii)
From your titration results obtain a volume of B to be used in your calculations.
Show clearly how you obtained this volume.
volume of B = ............................................... cm3
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For
Examiner’s
Use
9
(iii)
For
Examiner’s
Use
Suggest why a separate indicator is not needed in this titration.
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Calculations
(iv)
Calculate the concentration, in mol dm–3, of iron(II) ions in A.
Show your working. Give appropriate significant figures in your answers.
The equation for the reaction is
5Fe2+
+
MnO4–
+
8H+
5Fe3+
+
Mn2+
+
4H2O
concentration = ....................................... mol dm–3
(v)
Use your answer from (a)(iv) to calculate the concentration of iron(II) ions, in
g dm–3, in A.
concentration of iron(II) ions in A = .......................................... g dm–3
Question 2 continues on the next page.
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Chemical Tests
(b) (i)
For
Examiner’s
Use
Carry out the following tests on solution C.
Record your observations in the table below.
test
observations
Put 1 cm of depth of C into a
test-tube.
Add aqueous sodium hydroxide,
drop by drop with shaking, until
the test-tube is about half-full.
Stand the test-tube in a beaker
half-filled with very hot water.
Test any gas evolved with both
damp red litmus paper and
damp blue litmus paper.
Put 1 cm depth of C into a
test-tube.
Add 10 drops of aqueous
hydrogen peroxide. (You may
see bubbles of oxygen.)
(ii)
Identify the two cations present in C. Give evidence to support your conclusions.
cation 1 .....................................................................................................................
evidence ...................................................................................................................
..................................................................................................................................
cation 2 .....................................................................................................................
evidence ...................................................................................................................
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(iii)
Explain the effect of adding aqueous hydrogen peroxide to C.
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[Total: 15]
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11
Qualitative Analysis Notes
Key: [ppt. = precipitate]
1
Reactions of aqueous cations
reaction with
NaOH(aq)
NH3(aq)
aluminium,
Al 3+(aq)
white ppt.
soluble in excess
white ppt.
insoluble in excess
ammonium,
NH4+(aq)
no ppt.
ammonia produced on heating
barium,
Ba2+(aq)
no ppt. (if reagents are pure)
no ppt.
calcium,
Ca2+(aq)
white ppt. with high [Ca2+(aq)]
no ppt.
chromium(III),
Cr3+(aq)
grey-green ppt. soluble in excess
giving dark green solution
grey-green ppt.
insoluble in excess
copper(II),
Cu2+(aq)
pale blue ppt.
insoluble in excess
blue ppt. soluble in excess
giving dark blue solution
iron(II),
Fe2+(aq)
green ppt. turning brown on contact
with air
insoluble in excess
green ppt. turning brown on contact
with air
insoluble in excess
iron(III),
Fe3+(aq)
red-brown ppt.
insoluble in excess
red-brown ppt.
insoluble in excess
lead(II),
Pb2+(aq)
white ppt.
soluble in excess
white ppt.
insoluble in excess
magnesium,
Mg2+(aq)
white ppt.
insoluble in excess
white ppt.
insoluble in excess
manganese(II),
Mn2+(aq)
off-white ppt. rapidly turning brown
on contact with air
insoluble in excess
off-white ppt. rapidly turning brown
on contact with air
insoluble in excess
zinc,
Zn2+(aq)
white ppt.
soluble in excess
white ppt.
soluble in excess
[Lead(II) ions can be distinguished from aluminium ions by the insolubility of lead(II) chloride.]
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2
Reactions of anions
ion
reaction
carbonate,
CO32–
CO2 liberated by dilute acids
chromate(VI),
CrO42– (aq)
yellow solution turns orange with H+(aq);
gives yellow ppt. with Ba2+(aq);
gives bright yellow ppt. with Pb2+(aq)
chloride,
Cl – (aq)
gives white ppt. with Ag+(aq) (soluble in NH3(aq));
gives white ppt. with Pb2+(aq)
bromide,
Br – (aq)
gives pale cream ppt. with Ag+(aq) (partially soluble in NH3(aq));
gives white ppt. with Pb2+(aq)
iodide,
I – (aq)
gives yellow ppt. with Ag+(aq) (insoluble in NH3(aq));
gives yellow ppt. with Pb2+(aq)
nitrate,
NO3– (aq)
NH3 liberated on heating with OH–(aq) and Al foil
nitrite,
NO2– (aq)
NH3 liberated on heating with OH–(aq) and Al foil,
NO liberated by dilute acids
(colourless NO → (pale) brown NO2 in air)
sulfate,
SO42– (aq)
gives white ppt. with Ba2+(aq) or with Pb2+ (insoluble in excess dilute
strong acid)
sulfite,
SO32– (aq)
SO2 liberated with dilute acids;
gives white ppt. with Ba2+(aq) (soluble in excess dilute strong acid)
3
Tests for gases
gas
test and test result
ammonia, NH3
turns damp red litmus paper blue
carbon dioxide, CO2
gives a white ppt. with limewater
(ppt. dissolves with excess CO2)
chlorine, Cl 2
bleaches damp litmus paper
hydrogen, H2
“pops” with a lighted splint
oxygen, O2
relights a glowing splint
sulfur dioxide, SO2
turns acidified aqueous potassium dichromate(VI) (aq) from orange to
green
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University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of
Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
© UCLES 2013
8780/04/O/N/13